Nonoxynol or nonylphenol(polyethoxy)ethanol is a nonionic surfactant used as the active ingredient in the majority of the commercially available spermicides. It inhibits the in vitro growth of venereal pathogens (see Benes, S. et al., (1985) Antimicrob. Agent Chemother. 27: 724-726; Kelly, J. P. et al., (2985), Antimicrob. Agent Chemother 27: 760-762; Austin, H., et al., (2984) JAMA, 251: 2822-2824; and Singh, B. et al., (1972) Br. J. Vener. Dis. 48: 57-64), including the herpes simplex viruses (see Asculai, S. S. et al., (1978) Antimicrob. Agent Chemother. 13: 686-690; Hicks, D. R., (1985) Lancet, 1422-1423; Friedman-Kein, (1986) J. Am. Acad. Dermol. 15: 989-994; Rapp, R. et al., (1985) Antimicrob. Agent Chemother. 28: 449-451; Voeller, B., (1986) Lancet, 1153; Malkovsky, M. et al., (1988) Lancet, 645; and Barbi, M. et al., (1987) Boll. 1st. Sieroter. (Milan) 66: 158-160).
By the nature of its synthesis, the nonoxynol-9 (N-9) (Igepal CO-630) derivative of nonoxynol is a polymer consisting of at least 17 oligomers of varying ethylene oxide (EO) chain length. The molecule of N-9 contains a hydrophobic moiety (nonylphenol portion) and a hydrophilic chain composed basically of ethylene oxide units. The compound is a product of a statistical polymerization reaction of 9 moles of ethylene oxide and one mole of nonylphenol (see equation below): ##STR1## where "n" represents the number of ethylene oxide units.
The above reaction does not yield a distinct compound but a mixture of oligomers with different molecular weights. The physical and chemical characteristics of these oligomers change as a function of the varying molecular weight. (See Liebert, M. A., (1983) J. Am. Coll. Toxicol. 2: 35-60). As the length of the EO chain increases, the oligomers increase in water solubility. Nonoxynol-9 oligomers 1 through 6 (n=1-6) are considered oil soluble compounds, whereas the oligomers with a longer EO chain are soluble in water and polar organic solvents (see Liebert, supra).
These differences in chemical properties of N-9 oligomers affect their biological behavior both in vitro and in vivo. For instance, it was noted that the dermal toxicity of nonoxynol decreases as the molecular weight increases (see Liebert, supra) and that smaller molecular weight nonoxynol may be more toxic to fibroblasts than the larger ones (see Chvapil, M. et al., (1980) Fertil. Steril. 33: 521-525).
The in vitro spermicidal activity of the N-9 surfactant is also related to its molecular weight. Thus the oligomer n=9 when separated from the N-9 compound, was much more effective in inhibiting the motility of the spermatozoa than the higher molecular weight nonoxynols where n =30, 50, and 100. (See Chvapil, M. et al., (1980) Fertil. Steril. 33: 521-525.) The lower molecular weight nonoxynols (n=1 or 4) could not be studied appropriately because of their poor solubility in the aqueous testing medium (see Chvapil, supra).
Analogous dependence on molecular weight was observed in vivo. Oral absorption studies in the rat indicated that increasing the length of the ethylene oxide chain decreased N-9 oligomer intestinal absorption (see Knaak, J. B. et al., (1966) Toxicol. Appl. Pharmacol. 9: 331-340). Furthermore, data showed that absorption of N-9 through the vaginal membrane was poor and reflects the preferential absorption of lyophilic low molecular weight oligomers. (See Walter, B. A. et al. (1988) Toxicol. Applied Pharmacol. 96: 258-268.)
An efficient high pressure liquid chromatography (HPLC) method for the separation of [.sup.14 C]N-9 and characterization of the oligomeric components of the spermicide N-9 has been developed. (See Walter, B. A. et al. (1988) Toxicol. Applied Pharmacol. 96: 258-268; and Walter, B. A. et al., (1991) Pharm. Res. 8: 409-411).
Utilizing this normal phase gradient elution HPLC method, at least seventeen oligomers were isolated from commercial N-9. Selected oligomers representing the high, medium and low molecular weight fraction of N-9 were separated in milligram quantities by normal phase gradient HPLC (see Waiter, B. A. et al., (1991) Pharm. Res. 8: 409-411; and Walter, B. A. et al., (1991) Pharm. Res. 8: 403-408).
Polyvinylpyrrolidone (also known as povidone USP) is one of the most highly utilized polymers in medicine because of its safety for human use and unique hydrophilic properties (see Robinson, B. V. et al. (1990), A critical review of the Kinetics and Toxicology of Polyvinyl-pyrrolidone, Lewis Publishers, Inc., Michigan).
Discovered and used during World War II as a plasma expander, PVP is currently used as excipient in many pharmaceutical preparations intended for external use (e.g. povidone-iodine USP solutions such as Betadine); for oral use, such as a solubilizing agent and tablet disintegrant, and fox vaginal use such as in PVP-I douche.
Several studies have focused on the dissolution rate behavior of drug-povidone coprecipitates. (See Higuchi, W. I. et al., (1983) in Proceedings of the International Symposium on Povidione, Digenis, G. A. and Arisell, J., Eds. Lexington, pp. 71-79; Simonelli, A. P. et al., (1987) in Proceedings of the 2nd International Symposium on Povidone, Digenis, G. A. and Agha, B. J., Eds., Lexington, pp. 392-401; Simonelli et al., (1969) J. Pharm. Sci., 58: 538-549; Simonelli et al. (1976) ibid. 65: 355-361.)
These studies found that the preferential dissolution of one component (hydrophilic polymer, such as PVP) can enhance the dissolution of the other component in a coprecipitate.
Drug/PVP high energy coprecipitates can be described as a drug incorporated into a solid PVP solution. Drug release from PVP coprecipitates are shown to follow dissolution kinetics of the polymer carrier of PVP provided that the PVP solvent uptake or swelling proceeds freely without inhibition by the drug.
Mayersohn and Gibaldi (Mayersohn M. et al., (1966) J. Pharm. Sci. 55: 1323-1324) showed greatly enhanced dissolution of the antibiotic griseofulvin when the drug was coprecipitated with povidone (PVP). Higuchi et al. investigated a povidone/sulfathiazole system and suggested that the resultant enhanced aqueous solubility of sulfathiazole was due to a high energy state of the drug in the PVP coprecipitate resulting in a supersaturated form of the drug after introduction into aqueous media. (See Higuchi, W. I. et al., (1983) in Proceedings of the International Symposium on Povidione, Digenis, G. A. and Ansell, J., Eds. Lexington, pp. 71-79.)
Simoneill et al., envisioned a PVP/drug coprecipitate model consisting of two components including the drug in amorphous state and PVP. (Simonelli, A. P. et al., (1987) in Proceedings of the 2nd International Symposium on Povidone, Digenis, G. A. and Agha, B. J., Eds., Lexington, pp. 392-401; Simonelli et al., (1969) J. Pharm. Sci. 58: 538-549; Simonelli et al. (1976) ibid. 65: 355-361.)
The in vitro spermicidal activity of three molecular weight fractions of N-9 were compared to that of N-9, using rabbit spermatozoa, at equimolar concentrations. nonoxynol-9/PVP complexes were found to be far more effective in immobilizing the sperm than either N-9 alone or in the separate fractions (Walter, B. A. et al., (1991) Pharm. Res. 8: 403-408).
The spermicidal activities of three oligomeric fractions of N-9 with human sperm have been assessed. Equimolar concentrations of three different molecular weight fractions of N-9 coprecipitated with PVP were used. These equimolar concentrations were 166 .mu.g/ml for high molecular weight (HMW), (MW=599), 123 .mu.g/ml for middle molecular weight (MMW&gt;(MW=499) and 85 .mu.g/ml for low molecular weight (LMW) (MW=306) N-9 fractions. The order of efficacy in immobilizing the human spermatozoa was HMW(MW=599)&gt;MMW(MW=499)&gt;LMW(MW=306) with complete sperm immobilization observed with PVP coprecipitated with N-9 HMW within 4.0 minutes and PVP coprecipitated with N-9 MMW within 15 minutes after exposure. Furthermore, addition of the spermicides interfered with the progressive motility and linearity of the sperm swimming pattern. PVP and buffer controls showed no decline in percentage motility over the course of the test.
Chvapil et al. recognized that the n=9 oligomeric fraction of nonoxynol-9 was more effective in inhibiting the motility of spermatozoa than the higher molecular weight nonoxynols. Chvapil et al., however, were unable to study the lower molecular weight oligomers (n=1-4) because of their poor solubility in aqueous media.
In contrast, however, Walter et al. were able to solubilize the water insoluble lower molecular weight N-9 oligomers by complexing them with the hydrophilic polymer polyvinylpyrrolidone (PVP). (See Walter, B. A. et al., (1991) Pharm. Res. 8: 403-408.)
The resulting high energy coprecipitate complexes of the low molecular species of N-9 were found to be at least effective spermicides at all concentrations tested when compared to their counterparts that were prepared from higher molecular weight N-9 oligomeric fractions. However, they were themselves effective spermicides. The above findings concluded that when N-9 is coprecipitated with PVP its spermicidal activity is enhanced. While PVP alone has no inherent sperm toxicity, the formation of N-9/PVP complexes seem to produce a synergistic response which causes a more rapid damage to the sperm than any of the two materials alone (Walter, B. A. et al., (1991) Pharm. Res. 8: 403-408).
Nonoxynol-9 (N-9) has been shown to be useful in the prophylaxis against sexually transmitted diseases (STD). (See Bird, K. D., (1991) AIDS 5: 791-796; and Louv, W. C. et al., (1988) J. Infect. Dis. 158: 518-523).
More recently, this spermicide has been shown to be effective against cell-associated HIV at concentrations of .gtoreq.0.05% (v/v). (See Hicks, D. R. et al., (1985) Lancet, ii: 1422-1423; Vopeller, B., (1986) Lancet, i: 1153; and Malkovsky, M., Newell, A., Dalgleish, A. G., (1988) Lancet, i: 645).
Unfortunately, N-9 causes epithelial disruption of the cervix and vagina when administered in high doses and high frequency (see Niruthisard S. et al., (1991) Sex. Transm. Dis. 18: 176-179). Higher rates of new HIV infections were found in prostitutes who used N-9 at great frequencies (see Kreiss, J. et al., International Conference on AIDS, Montreal, June 1989 [Abstract MAO36]). This observation was attributed to the high incidence of genital ulceration caused by high doses of N-9, in this group of women. Thus, the above findings tend to suggest that novel spermicide formulations containing N-9 should be efficacious at the smallest possible doses so that the integrity of the vaginal epithelium is not compromised.
The antimicrobia properties of povidone-iodine (PVP-I), a complex of polyvinyl pyrrolidone and iodine, have been well documented. PVP-I solutions (10% w/v) USP are among the most widely utilized antimicrobial agents. A 10% (w/v) solution of PVP-I contains 1% (w/v) of available iodine (I.sub.2). The microbiological potency of PVP-I arises from the elemental (diatomic) or free iodine (I.sub.2) in solution. The significant characteristic of iodophores, such as PVP-I, is that they carry almost all of their iodine in a complexed form so that the amount of free iodine (I.sub.2) is quite low and PVP-I serves as the iodine reservoir delivering the free iodine into the solutions. Thus, iodophors exhibit reduced irritation properties and are relatively non-toxic (see LaRocca, R. et al., (1983) in Proceedings of the International Symposium on Povidone, Digenis, G. A. and Ansell, J., Eds. Lexington, pp. 101-119).
Stable, sterile (0.2%) PVP-I compositions containing as little as 0.02% iodine have been shown to be useful in treating eye infections in humans. A level of 0.02% iodine obtained by diluting a commercial 10% PVP-I solution at 1:50 with saline solution, is generally considered to be optimum to maximize performance and minimize irritation (see Winicov, M. et al., (1987) in Proceedings of the International Symposium on Povidone, Digenis, G. A. and Ansell, J., Eds. Lexington, pp. 57-64).
Data has shown that with doubly labeled .sup.14 C-PVP-.sup.131 I solutions the amount of iodine delivered into gram positive and negative bacteria cultures was three times greater when the iodine was complexed with PVP, than from an equimolar solution of .sup.131 I.sub.3 --(Lugol's solution). (See Digenis, G. A. et al., (1983) in Proceedings of International Symposium on Povidone, Digenis, G. A. and Ansell, J., Eds. Lexington, pp. 302-311).
The hydrophilic polymer PVP acts as a delivery system for iodine probably due to the membrane seeking properties of this polymer. Ben-David and Gavendo have shown that PVP at 4.6% w/v concentrations protect red blood cells from osmotic fragility and mechanical injury. (See Ben-David A. et al., (1972) Cryobiology, 9: 192-197). These workers suggested that this effect is brought about by a "coating" or external interaction of PVP with cell membranes.
The membrane-seeking properties of PVP suggest that in addition to its contribution to the solubilization ability of N-9, the PVP polymer, via its cell-membrane coating properties, also provides vaginal and cervical surface coverage coating with N-9 and iodine over extended periods of time.
In addition to its antimicrobial properties, PVP-I has been shown to inactivate HIV. (See Kaplan, J. C. et al. (1987) Infect. Control 8: 412-424; and Harbison, M. A. et al., (1989) J. Acquir. Immune Defic. Syndr. 2: 16-20). The concentration of iodine used in Kaplan's studies was equal to 0.025% for 250 ppm of I.sub.2.
A 0.02% w/v (200 ppm) solution of iodine is considered non-toxic and non-irritating and is used for treatment of eye infections in humans. (See Winicov, M. et al., (1987) in Proceedings of the International Symposium on Povidone, Digenis, G. A. and Ansell, J., Eds. Lexington, pp. 57-64). In fact, the increased bactericidal activity of dilute solutions of povidone-iodine (Betadine--10% w/v PVP-I) have recently been well documented. Betadine contains 10,000 ppm (or 10,000 .mu.g/ml) of available iodine and is often irritating to the tissues and has an undesirable brown color. (See Berkelman, R. L. et al., (1982) J. Clin. Microbiol. 15: 635-639.) At concentrations of about 0.02% w/v of iodine, the undesirable brown color of iodine is not a problem since in dilute solutions the color is hardly seen and the amount of iodine is not irritating to tissues.
None of the prior research in this area recognized the synergistic anti-HIV result of all three compounds when formulated into a high energy coprecipitate.
Furthermore, spermicides containing nonoxynol-9 and polyvinylpyrrolidone or polyurethane are known.
U.S. Pat. No. 4,317,447 to Williams discloses a device for delivering a medicament to the vaginal cavity consisting of a molded sheath of a mixture of a polymeric material and a medicament. The medicament which is dispersed in the polymeric material can be nonoxynol-9. The polymer may be selected from modified cellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic and ethylene oxide polymer. Williams does not disclose the use of PVP-I in combination with a nonoxynol-9.
U.S. Pat. No. 5,156,164 to LeVeen et al. discloses that iodine can be dissolved in alcohol containing nonoxynol in a complex with polyurethane. LeVeen et al. disclose that a polyvinylpyrrolidone-iodine complex has been effective in treating resistant vaginitis. LeVeen et al. do not disclose or suggest combining PVP-I with nonoxynol.
U.S. Pat. No. 5,070,889 to Leveen et al. discloses a contraceptive sponge and tampon made of polyurethane iodine complex. Leveen et al. teaches away from the use of povidone iodine or use as a contraceptive.
U.S. Pat. No. 5,073,365 to Katz et al. discloses clinical and personal care articles enhanced by lubricants and adjuvants. The devices can be made of polyvinylpyrrolidone or polyurethane interpolymers. The device may take the form of vaginal diaphragms, tampons, condoms or cervical caps. The medicament may be nonoxynol-9. Katz et al. disclose that the personal care articles may prevent the transmission of venereal diseases, possibly including AIDS.
U.S. Pat. No. 4,707,362 to Nuwayser discloses a sustained release composition made of synthetic polymers such as polyvinylpyrrolidone. The bioerodible material in one embodiment has been modified so that a spermicide such as nonoxynol-9 is slowly released. Nuwayser does not disclose PVP-I in combination with nonoxynol-9.
U.S. Pat. No. 4,954,351 to Sackler et al. discloses a method of producing standardized povidone-iodine preparations. The patent discloses that the povidone-iodine solution can be incorporated into a suppository with 0.1 to 10% by weight of povidone-iodine. Sacklet et al. do not disclose the use of povidone-iodine in combination with nonoxynol-9.
U.S. Pat. No. 4,297,341 to Waller et al. discloses that a water-soluble complex comprising polyvinylpyrrolidone and gossypol is an effective spermicide. The patent discloses that a PVP-gossypol combination when compared to a comparative example of nonoxynol-9 alone, exhibited equal or greater spermicidal properties. Waller does not disclose PVP-I in combination with nonoxynol-9.
U.S. Pat. No. 4,925,033 to Stoner et al. discloses a microbicidal cleanser/barrier kit. One method of the invention involves applying a solution of povidone-iodine (PVP-I) to vaginal sponges or condoms. In another embodiment the povidone-iodine active ingredient may be added to spermicidal birth control compounds. Stoner et al. disclose that nonoxynol-9 is a known spermicidal compound. Stoner et al. do not disclose or suggest the particular combination of components in the form of a high energy coprecipitate, nor that the compounds show a synergistic anti-HIV effect.
Heterosexual transmission of human immunodeficiency virus (HIV), the causative agent of AIDS, is a growing concern in the United States where 37% of AIDS cases are heterosexually transmitted, the majority being male-to-female. Moreover, the frequency of global heterosexual transmission is probably greater where it is estimated to exceed 60% of all AIDS cases.
It has been suggested that a major contributing factor to heterosexual transmission of HIV is the presence of cell-free virus and virus-infected cell (cell-associated virus in genital secretions. Thus, vaginal contraceptives which inactivate HIV should be an effective barrier to transmission.
There is a need in the pharmaceutical area for a a contraceptive with potent anti-HIV activity. Ideally, a contraceptive agent is needed that can:
1a) provide rapid spermicide delivery (within 30-60 seconds); PA1 1b) provide long-actingspermicidal activity after a single application; PA1 2) protect the user against HIV (AIDS) and other sexually transmitted diseases (STDs); PA1 3) protect vaginal and cervical epithelia from irritation; PA1 4) enhance penetration of spermicide into cervical mucus; PA1 5) exhibit low systemic bioavailability (low absorption); PA1 6) be pharmaceutically and cosmetically acceptable (e.g. a tablet or capsule are preferred, as suppositories, creams and gels appear not to be as attractive to young users). PA1 (a) fractionating commercially available spermicide N-9 to seventeen oligomers by a preparative high pressure liquid chromatography (HPLC) procedure; and PA1 (b) converting the oligomers or commercially available N-9 to a high energy coprecipitate with PVP and iodine. PA1 (a) fractionating commercially available spermicide nonoxynol-9 (N-9) to seventeen oligomers by high pressure liquid chromatography (HPLC); PA1 (b) adding an N-9 oligomer obtained in step (a) with a 10% or 1% solution w/v of PVP-I in a solvent, PA1 (c) placing the product of step (b) in an oil bath at about 100.degree. C., and allowing the solvent to evaporate. PA1 (d) obtaining a high energy coprecipitate of N-9, polyvinylpyrrolidone (PVP) and iodine.
The composition of the invention meets the above objectives and provides a high energy coprecipitate of nonoxynol-9 oligomers, polyvinylpyrrolidone and iodine (PVP-I). The composition shows a pronounced synergistic effect between the compounds which results in potent anti-HIV activity. The composition of the invention safely and cost-effectively provides a contraceptive with potent anti-HIV activity.